[sdiy] 2n3904 transistor matching stats

Dave Brown davebr at modularsynthesis.com
Wed Jun 8 07:43:03 CEST 2016

I just built a design for a customer that needed 6 matched pair of 2N3906s.  I bought them on cut tape and verified matching with my 577 curve tracer.  I was literally unable to tell any difference between adjacent pairs.  Then I tested the 1st on the cut tape against the 12th and I could detect a very minor difference.  I was impressed.


Then I tested a random batch of loose transistors of another type.  There were more significant differences but it seemed like a Gaussian distribution with many close in characteristics and a few outliers.  It was much tighter than I expected, but for all I know they came out of the same batch as they were not a high volume runner.



From: Synth-diy [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Pete Hartman
Sent: Tuesday, June 07, 2016 6:01 PM
To: Mike Beauchamp
Cc: synthdiy diy
Subject: Re: [sdiy] 2n3904 transistor matching stats


I haven't noticed, but I haven't done rigorous checking either

On Jun 7, 2016 4:18 PM, "Mike Beauchamp" <list at mikebeauchamp.com> wrote:

On 06/07/2016 07:12 PM, Pete Hartman wrote:

I've found that transistors on a tape almost always have very close
matching between adjacent devices.  To the point where I only bother to
check if I have some other reason to want them to be extra precise (e.g.
If I'm building for someone other than myself)

Did you ever notice any that weren't matched?

These were just ordered in a loose bag, so maybe the outliers were from a different manufacturing run.


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